feat(ai-gemini): support Nano Banana 2 Lite (gemini-3.1-flash-lite-image)

[tombeckenham]

🎯 Changes

Adds proper support for Nano Banana 2 Lite (gemini-3.1-flash-lite-image) to the Gemini adapter, and fixes the model-sync bug that mis-landed it.

Background: the automated OpenRouter sync (#772) had already added gemini-3.1-flash-lite-image to main — but mis-classified as a text-only chat model (output: ['text'], listed in GEMINI_MODELS + the chat type maps). Verified against the live Gemini API, it's a native image model (generateContent → inline image, ~1120 tokens/1K image).

This PR:

• Corrects the model entry and wires it into the image surface — output: ['text', 'image'], in the image-model region + GEMINI_IMAGE_MODELS, added to the GeminiNativeImageModels union (template-literal sizes like "1:1_2K", image-conditioned prompts) — matching the other native image models. Removed from the chat arrays/type maps.
• Fixes the sync generator (scripts/sync-provider-models.ts): the guard isImageOnlyModel (image output and not text) → outputsImage (any image output), so native text+image image models are skipped for manual curation instead of being inserted as chat models. Verified against scripts/openrouter.models.json: all six gemini-*-image models flip from "added to chat" → "skipped".
• Unit test asserting native generateContent routing + size parsing for the new model.
• Docs (docs/adapters/gemini.md, docs/media/image-generation.md + updatedAt), and the media-generation skill model list.

Scope note: this issue was split — Gemini Omni Flash (gemini-omni-flash-preview) needs a separate Interactions-API path and is tracked in #871.

Closes #870.

✅ Checklist

• I have followed the steps in the Contributing guide.
• I have tested this code locally with pnpm run test:pr.

🚀 Release Impact

• This change affects published code, and I have generated a changeset.
• This change is docs/CI/dev-only (no release).

Summary by CodeRabbit

• New Features

  • Added support for a new Gemini native image model, “Nano Banana 2 Lite,” for faster, lower-cost image generation.
  • Improved image generation handling for mixed text-and-image output models, including better size and prompt support.

• Bug Fixes

  • Correctly routes the new model through the native image generation flow instead of treating it as a chat model.
  • Prevents image-capable models from being incorrectly included in manual model lists.

• Documentation

  • Updated image model availability and Gemini adapter docs to include the new model.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: 97521935-1e4f-4c0f-b825-e136955adf62

📥 Commits

Reviewing files that changed from the base of the PR and between 00505fe and a7b672d.

📒 Files selected for processing (9)

• .changeset/gemini-nano-banana-2-lite.md
• docs/adapters/gemini.md
• docs/config.json
• docs/media/image-generation.md
• packages/ai-gemini/src/image/image-provider-options.ts
• packages/ai-gemini/src/model-meta.ts
• packages/ai-gemini/tests/image-adapter.test.ts
• packages/ai/skills/ai-core/media-generation/SKILL.md
• scripts/sync-provider-models.ts

---

📝 Walkthrough

Walkthrough

Reclassifies gemini-3.1-flash-lite-image (Nano Banana 2 Lite) from a Gemini chat model to a native Gemini image model. Updates metadata, type maps, and image-provider option unions, adds a routing test, updates the OpenRouter sync script's image-model exclusion logic, and refreshes related docs.

Changes

Nano Banana 2 Lite image model registration

Layer / File(s)	Summary
Model metadata and classification packages/ai-gemini/src/model-meta.ts	GEMINI_3_1_FLASH_LITE_IMAGE metadata updated (token limits, modalities); moved from GEMINI_MODELS to GEMINI_IMAGE_MODELS; removed from GeminiChatModelProviderOptionsByName and GeminiModelInputModalitiesByName.
Native image model type wiring packages/ai-gemini/src/image/image-provider-options.ts	Added 'gemini-3.1-flash-lite-image' to the GeminiNativeImageModels union.
Image adapter test coverage packages/ai-gemini/tests/image-adapter.test.ts	New test asserting generateImage routes through generateContent with correct imageConfig and response parsing.
OpenRouter sync exclusion update scripts/sync-provider-models.ts	Replaced isImageOnlyModel with outputsImage, excluding any model that outputs image (including text+image) from chat model curation.
Docs, skill list, and changeset docs/adapters/gemini.md, docs/media/image-generation.md, packages/ai/skills/ai-core/media-generation/SKILL.md, docs/config.json, .changeset/gemini-nano-banana-2-lite.md	Added the new model entry to documentation tables and skill list, bumped updatedAt timestamps, and added a changeset describing the changes.

Estimated code review effort: 2 (Simple) | ~15 minutes

Sequence Diagram(s)

Not applicable — changes are model registration/metadata and documentation updates without new multi-component control flow.

Suggested reviewers: AlemTuzlak

Poem

A tiny rabbit hops with glee,
Nano Banana 2 Lite, fast and free!
From chat to image, it found its lane,
generateContent — no more disdain 🎨
Docs and tests all lined in a row,
Hop hop hop, watch this model glow! 🐇✨

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly and concisely describes the main change: adding support for Nano Banana 2 Lite in the Gemini adapter.
Description check	✅ Passed	The description follows the required template and covers changes, checklist, and release impact.
Linked Issues check	✅ Passed	The PR implements the Nano Banana 2 Lite support requested in #870, including model registration, native routing, size parsing, tests, and docs.
Out of Scope Changes check	✅ Passed	The additional docs, tests, changeset, and sync-script updates support the stated Gemini image-model change.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch 870-support-google-omni-and-nb-lite

---

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[github-actions]

🚀 Changeset Version Preview

3 package(s) bumped directly, 0 bumped as dependents.

🟨 Minor bumps

Package	Version	Reason
@tanstack/ai-gemini	0.18.4 → 0.19.0	Changeset

🟩 Patch bumps

Package	Version	Reason
@tanstack/ai-anthropic	0.15.12 → 0.15.13	Changeset
@tanstack/ai-react	0.16.1 → 0.16.2	Changeset

[nx-cloud]

View your CI Pipeline Execution ↗ for commit a7b672d

Command	Status	Duration	Result
nx run-many --targets=build --exclude=examples/...	✅ Succeeded	9s	View ↗

---

☁️ Nx Cloud last updated this comment at 2026-07-01 02:47:39 UTC

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commit: a7b672d